Duct problem

I have a forced hot air heating system in my home. There are two bedrooms that virtually get no heat. Barely any air comes out of the vents while other rooms get plenty of warm air. There either has to be a duct separtion somewhere in the wall or floor or there is a buried damper somewhere that is blocking the flow of air. I've heard of something I think is called "videoscoping", where a camera built into a cable is dropped down the duct to see where the problem might be. Anyone familiar with what I'm referring to? Please advise.

Duct problem

Duct problem

shut the rooms that are blasting and see if you get anything or noise of the air leaking on closed dampers........being buried are you talking metal duct work or flex laying under the houses foundation and run up?

Duct problem

It's metal ducts. The house is a split level so the duct work travels three floors up with a main trunk line buried in the wall. I don't think there's any way to hear air leaking even with a stethiscope.